PROJECT SUMMARY Infection of humans with Plasmodium falciparum parasites results in significant morbidity and mortality. The pathogenesis of malaria is associated with the sequestration of parasite-infected red blood cells through their cytoadherence to vascular walls. PfEMP1 has been identified as the key parasite molecule on the red blood cell surface that mediates this binding, and much effort has gone into the identification of the specific PfEMP1 protein motifs and critical parasite molecules that are required for protein trafficking and export into the red blood cell. In this work, we seek to identify red blood cell molecules within the red blood cell proteome that effect protein trafficking to the surface of red blood cells. We will develop genetic screening systems to conduct complementary knockdown and knockout screens using CD34+ hematopoietic cells followed by in vitro culture of red blood cells to produce mutant red blood cells. Specifically, we will identify molecules that are required for trafficking of the virulence protein PfEMP1 to the surface of the red blood cell. The identification of specific host red blood cell molecules and pathways in PfEMP1 trafficking to the host red blood cell will greatly enhance our understanding of host-parasite interactions during the transformation of the host red blood cell, and will aid in devising strategies that therapeutically target protein trafficking. Moreover, the development of red blood cell genetic screening methodologies will allow the study of numerous interactions between the red blood cell and Plasmodium spp. parasites.